High-Pressure Homogenization: An Industrially Scalable Method for Producing PHBH Powders for Selective Laser Sintering

Abstract

Selective laser sintering (SLS) enables the production of high-quality, complex plastic components without requiring support structures. However, the widespread adoption of SLS is constrained by limited material availability, mainly synthetic polymers, and the inefficiency of laboratory-scale methods, such as solvent phase separation, for producing new polymer powders. This study explores high-pressure homogenization (HPH) as a purely mechanical and solvent-free method for micronizing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), a biodegradable co-polyester, into particles suitable for SLS. The influence of key HPH parameters, including pressure and number of passes, on particle morphology and size distribution is evaluated. Under optimal conditions, 18 passes at 1000 bar, a median particle size of 49 µm is achieved, with powders exhibiting sub-rounded morphology (median circularity of 0.944) and sufficient flowability, as indicated by a Hausner ratio of 1.34, making them suitable for SLS processing. The 3D printability is tested on both simple and complex geometries, which all result in 95% dense final components. Thermal characterization indicates that the PHBH powders retain suitable thermal stability, with degradation temperatures exceeding the SLS processing range. Mechanical testing of 3D printed parts reveals Young's modulus of 160 MPa and a maximum storage modulus of 2.7 GPa at −10 °C.